The aim of the present study is to assess the impact of CYP3A4-induction by SJW on steady state ambrisentan and the impact of the cytochrome P450 2C19 (CYP2C19) genotype (*2 and *3 allele vs. wild type; ~2-5% poor metabolisers in Caucasian population) on the pharmacokinetics of ambrisentan in healthy volunteers.